The countries by which Parthia Proper was bounded were the following: Chorasmia, Margiana, Aria, Sarangia, Sagartia, and Hyrcania.
Chorasmia lay upon the north, consisting of the low tract between the most northerly of the Parthian mountain chains and the old course of the Oxus. This region, which is for the most part an arid and inhospitable desert, can at no time have maintained more than a sparse and scanty population. The Turkoman tribes which at the present day roam over the waste, feeding their flocks and herds alternately on the banks of the Oxus and the Tejend, or finding a bare subsistence for them about the ponds and pools left by the winter rains, represent, it is probable, with sufficient faithfulness, the ancient inhabitants, who, whatever their race, must always have been nomads, and can never have exceeded a few hundred thousands. On this side Parthia must always have been tolerably safe from attacks, unless the Cis-Oxianian tribes were reinforced, as they sometimes were, by hordes from beyond the river.
On the north-east was Margiana, sometimes regarded as a country by itself, sometimes reckoned a mere district of Bactria. This was the tract of fertile land upon the Murg-ab, or ancient Margus river, which is known among moderns as the district of Merv. The Murg-ab is a stream flowing from the range of the Paropamisus, in a direction which is a little east of north; it debouches from the mountains in about lat. 36° 25’, and thence makes its way through the desert. Before it reaches Merv, it is eighty yards wide and five feet deep, thus carrying a vast body of water. By a judicious use of dykes and canals, this fertilizing fluid was in ancient times carried to a distance of more than twenty-five miles from the natural course of the river; and by these means an oasis was created with a circumference of above 170, and consequently a diameter of above fifty miles. This tract, inclosed on every side by deserts, was among the most fertile of all known regions; it was especially famous for its vines, which grew to such a size that a single man could not encircle their stems with his two arms, and bore clusters that were a yard long. Margiana possessed, however, as a separate country, little military strength, and it was only as a portion of some larger and more populous territory that it could become formidable to the Parthians.
South of Margiana, and adjoining upon Parthia toward the east, was Aria, the tract which lies about the modern Herat. This was for the most part a mountain region, very similar in its general character to the mountainous portion of Parthia, but of much smaller dimensions. Its people were fairly warlike; but the Parthian population was probably double or triple their number, and Parthia consequently had but little to fear in this quarter.
Upon the south-east Parthia was bordered by Sarangia, the country of the Sarangae, or Drangae. This appears to have been the district south of the Herat valley, reaching thence as far as the Hamoon, or Sea of Seistan. It is a country of hills and downs, watered by a number of somewhat scanty streams, which flow south-westward from the Paropamisus to the Hamoon. Its population can never have been great, and they were at no time aggressive or enterprising, so that on this side also the Parthians were secure, and had to deal with no formidable neighbor.
Sagartia succeeded to Sarangia towards the west, and bordered Parthia along almost the whole of its southern frontier. Excepting in the vicinity of Tebbes and Toun (lat. 34°, long. 56° to 58°), this district is an absolute desert, the haunt of the gazelle and the wild ass, dry, saline, and totally devoid of vegetation. The wild nomads, who wandered over its wastes, obtaining a scanty subsistence by means of the lasso, were few in number, scattered, and probably divided by feuds. Southern Parthia might occasionally suffer from their raids; but they were far too weak to constitute a serious danger to the mountain country.
Lastly, towards the west and the north-west, Parthia was bordered by Hyrcania, a region geographically in the closest connection with it, very similar in general character, but richer, warmer, and altogether more desirable. Hyrcania was, as already observed, the western and north-western portion of that broad mountain region which has been described as intervening between the eastern shores of the Caspian and the river Arius, or Heri-rud. It consisted mainly of the two rich valleys of the Gurghan and Ettrek, with the mountain chains inclosing or dividing them. Here on the slopes of the hills grow the oak, the beech, the elm, the alder, the wild cherry; here luxuriant vines spring from the soil on every side, raising themselves aloft by the aid of their stronger sisters, and hanging in wild festoons from tree to tree; beneath their shade the ground is covered with flowers-of various kinds, primroses, violets, lilies, hyacinths, and others of unknown species; while in the flat land at the bottom of the valleys are meadows of the softest and the tenderest grass, capable of affording to numerous flocks and herds an excellent and unfailing pasture. Abundant game finds shelter in the forests, while towards the mouths of the rivers, where the ground is for the most part marshy, large herds of wild boars are frequent; a single herd sometimes containing hundreds. Altogether Hyrcania was a most productive and desirable country, capable of sustaining a dense population, and well deserving Strabo’s description of it as “highly favored of Heaven.” The area of the country was, however, small, probably not much exceeding one half that of Parthia Proper; and thus the people were not sufficiently numerous to cause the Parthians much apprehension.
The situation and character of Parthia thus, on the whole, favored her becoming an imperial power. She had abundant resources within herself; she had a territory apt for the production of a hardy race of men; and she had no neighbors of sufficient strength to keep her down, when she once developed the desire to become dominant. Surprise has been expressed at her rise. But it is perhaps more astonishing that she passed so many centuries in obscurity before she became an important state, than that she raised herself at last to the first position among the Oriental nations. Her ambition and her material strength were plants of slow growth; it took several hundreds of years for them to attain maturity: when, however, this point was reached, the circumstances of her geographical position stood her in good stead, and enabled her rapidly to extend her way over the greater portion of Western Asia.